An Antifreezing, Tough, Rehydratable, and Thermoplastic Poly(vinyl alcohol)/Sodium Alginate/Poly(ethylene glycol) Organohydrogel Electrolyte for Flexible Supercapacitors

A hydrogel electrolyte is an ideal material for flexible energy storage equipment owing to its mechanical flexibility similar to solids and its ion transport ability analogous to liquids. However, a traditional hydrogel electrolyte cannot be remolded after forming and cannot be reused after dehydration. In addition, the traditional hydrogel electrolyte cannot work in a subzero environment. Here, the poly(vinyl alcohol)/sodium alginate/poly(ethylene glycol) (PVA/SA/PEG) organohydrogel electrolyte was successfully fabricated by a freezing–thawing process followed by soaking in a saturated NaCl aqueous solution. PEG could improve the mechanical property and endowed the organohydrogel with an excellent recyclability and healing ability. Meanwhile, PEG and NaCl in the organohydrogel also endowed the gel with low-temperature resistance. A new solution was provided to store and transport hydrogels by virtue of the good rehydration properties after the drying process. The flexible all-solid-state supercapacitor was fabricated by using activated carbon as the electrode and PVA/SA/PEG as the gel electrolyte. The flexible supercapacitors presented high areal capacitances of 103.6 mF cm–2 at 2 mA cm–2 at room temperature and 91.5 mF cm–2 at −15 °C. It is believed that the PVA/SA/PEG organohydrogel electrolyte with outstanding flexibility, freezing resistance, recyclability, and high ionic conductivity is a promising candidate for the next-generation flexible energy storage devices.